Electrical tap clamp



Nov. 14, 1950 F. J. HENDLEY ELECTRICAL TAP CLAMP Filed July 5, 1947 INVENTOR FLAVIUS JOSEPHUS HENDLEY5 DECEASED, BY, CORNELIA SMARTT HENDLEY,

EXECUTRIX BY 2410M flIZ Patented Nov. 14, x 1950 ELECTRICAL TAP CLAMP Flavius Josephus Hendley, deceased, late of Chattanooga, Tenn., by Cornelia Smartt Hendley, executrix, Columbia, Tenn.

Application July 5, 1947, Serial No. 759,116

The present invention relates to electrical connectors of the tap clamp type, such as are used in connecting-grounds or other leads to the electrical conductors which'form a part of a power distribution system.

, ;.;;The tap-clamps of the prior-art have the disadvantage that they soon provide poor contact -due to battering of themjetal by vibration, flow -of.-t he metalaway-from the contact pressure .points, mushingof conductor strands, backing EQfiFQf-the screw, and corrosion. r

The'conductors then become pitted, annealed,

orptherwise ruined from faults that are caused by thetap clamps of the prior art. Thousands of dollars are spent yearly to replace clamps and bad conductors that have been ruined by the burn-downs caused by these tap clamps.

--After years of service the clamps which have S. A. E. threads stick on the line. Corrosion binds the small closely fitted threads so that the clamp cannot be removed or tightened, thus becoming troublesome and dangerous. The standard threaded clamps of the prior art, when tightened ,up'in the beginning, have a contact area of littlemore' than a few points or-short lines, and are also subject to all of the foregoing disadvantages; eventually resulting in a bad connection, heating, burning ofthe conductor and clamp, etc.

A loosening or spacing of one ormore thou- ,sandths of an: inch between the clamping members and the line reduces the contact area and increases the contact resistance considerably, and the normal currents then pitand burn the contact areas more and more, with progressive steps 'of loosening and-burning until finally the;1ine

burns in two.

, One pf the objects of the present invention is ;the'-, p rovis ion of;an improved-tap. clamp of the classdescribed which is provided with a resilient gripper jaw that follows up-the flattening of the contact lines and gives a continued; firm contact throughout the life ofthe line and clamp, with aanenlarged contact areaand a continued carry- ..ingcapacity-for normal'and surge currents, substantially without the danger'of burn-down of the: conductor. i

Another object of the invention is the provision of gin-improved tap clamp provided with a resilient jaw which is also adapted to be tight- 8 Claims. (Cl. 173-273) ened to effect a rigid contact, leaving the resilient member to take up any slack that may later occur, and keeping a permanently firm contact.

Another object of the invention is the provision of an improved tap clamp with a resilient jaw which may be, provided with standard threads on a long threaded stem sleeve, the threads being fitted loosely, but the lower section of the stem being split and initially sprung inwardly to give a resilient clutching of' the threaded stem for the purpose of preventing back-out. 1

Another object of the invention is the provision of an improved tap clamp of the class described which has its threaded members so arranged that when there is corrosion, there is plenty of tolerance to permit the threads on the threaded eye bolt to pass through the firm internal threads at the upper section of the sleeve, the threaded bolt being resiliently clamped by a lower split section of the sleeve, which will give sufiiciently to prevent binding, and which will even permit a stem that is bent a small amount to be rotated to adjust the clamp without bindmg.

Another object of the invention is the provision of an improved tap clamp provided with gripper jaws, giving a maximum amount of contact, such asfour lines of contact, the jaws being curved to match the line sag tension by having the upper jaw bulge very slightly toward the center and the lower jaw being curved downwardly toward the'center to match the upper bulge.

A further object of the invention is the provision of an improved tap clamp of the class described which is provided with connection arrangements forthe jumper orv electrical conductor that extends downwardly from the tap clamp in such a manner that the jumper cannot pull out, being snubbed about a part of the tap clamp and insuch manner that jumpers can be attached to the clamp with a snubbing connection from the top, the bottom, or the back of the clamp.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawings, in which similar characters of reference indicate similar parts throughoutthe several views, 7 I

Referring to the single sheet of drawings,

Fig. l is a side elevational view of a tap clamp embodying my invention, shown in the open position, with the line conductor in dotted lines about to enter the jaws;

Fig. 2 is a front elevational view of the tap clamp in the open position;

Fig. 3 is a view similar to Fig. 2 of the tap clamp applied to the line conductor and having its resilient members compressed until the threaded member engages the lower clamping member and provides a rigid contact, with resilient take-up;

Fig. 4 is a transverse sectional view, taken on the plane of the line 44 of Fig. 1, looking in the direction of the arrows, showing the connector arrangements for the jumper wire;

Fig. 5 is a rear elevational view of the tap clamp; v v

Fig. 6' is a fragmentary vertical sectional view, taken on the plane of the line 66 of Fig. 2, looking in the direction of the arrows.

The tap-oiT clamps I0 embodying the present invention are preferably provided with a body member ll comprising a metal casting made of suitable electrically conducting metal, the body being formed with the upper clamping member 20, which comprises the main part of the jumper wire connector l4.

'The screw bolt 29 has a threaded shank 2| and a head 22. The head may be substantially rectangular in plan, as seen in Fig. 1, having a pair 'of parallel long sides 23 and a pair of parallel short sides 24. The longer dimension of the long sides 23 of the head 22 is for the purpose of permitting the head to span the jumper wire at two points, such as, for example, the jumper wire 25, which has an upwardly extendingportion 26, a

bend at 2'! around the lug i6, and a downwardly extending portion 28.

The lower side of 'theihead, which engages the jumper wire 25 at its portions 26 and 28, is preferablyformed with a pair of partially cylindrical grooves 29, 30 formed on a radius which is large enough to receive any jumper wire that is intended to be used with the tap clamp.

The web I3 underneath the head 22 is also formed with a pair of partially cylindrical grooves 3|, 32 for receiving the portions 26 and 28 of the jumper wire. The threaded shank 21 of the screw bolt '20 passes through the bore" l9 and is provided with a spring washer 33 and a nut 34, by means of which the shank is drawn through the bore l9, and the head 22 tightly clamps the jumper wire'inthe grooves 29, 3D, 3 I, 32.

In the example selected to illustrate the invention the jumper wire is inserted from the bottom, butit may just as well be inserted from the top, or from the back, at the point 35 on the web l3 (Fig. 1). In any case, the jumper wire is preferably provided with the U-shaped end portions 26, 27, 28, and it passes around the lug l8 and is clamped tightly at two points, thereby :giving a large contact-area and a snubbing action which prevents the jumper wire from dropping out, even if the screw bolt or nut should become loose.

The spring washer also aids in taking up any slack that may occur, and aids in preventing the nut from loosening.

The body H of the tap clamp has its web 13 provided with a forwardly extending, centrally located portion 35, which forms a part of the upper jaw i2. This jaw has a V-shaped opening formed by a pair of laterally projecting flanges 31, 38, which project from each side of the web portion 36 at an angle to each other to form the v-shaped trough [2.

The flanges 38 connect to a downwardly extending short flange portion 39, which connects to a downwardly and forwardly extending lip flange 40 on each side for the purpose of guiding the energized conductor 4| into the space between the jaws.

The body II also has a downwardly extending portion 42, which projects laterally from each side of the web l3 at its front side and joins to the flange portions 31 to form a guide for the movable jaw 43. Flanges 42 have a flat face 44 on the inside of the clamp opening; and the movable jaw 43 has a rear flat surface 45 for slidably engaging the guide surface 44.

The movable clamp 43 also has a pair of rear- 'wardly extending guide lugs 46, '41, which slidably engage the straight edges 48 of the flanges 42 for guiding the movable jaw and preventing its rotation.

The movable jaw 43 may consist of an elongated metal member, which is provided "with a V-shaped trough 49, the axis'of which is substantially parallel to the V-shaped' trough [2 in the fixed clamping member. The trough 49 is formed by a pair of surfaces 50, 5| at an angle to each other, and its length may be such that it extends beyond the flanges 31, 38 of the upper jaw on each side sufficiently to form the guide lugs 46, 47.

The movable jaw 43 also has a pair .of downwardly extending lugs 52, one at each end of the movable jaw 43 for securement of this jaw to a spring assembly 53. The downwardly extending lugs 52 on the movable jaw 43 may be rectangular in cross section, and may fit into complementary slots 54, which extend endwise into each end of the spring assembly 53.

The slots 54 are deeper than required, to receive the lugs'52 in the position of Fig. 2, so that the bases of the slots will not interfere with the movement of the spring assembly from'the bowed to the straight condition shown in Fig. 3.

The lugs 52 are riveted over at 55, below the spring assembly, thus fixedlysecuring the spring assembly at each end to the movable jaw 43. The spring assembly 53 may comprise a plurality of laminations of resilient leaf springs, such as phosphor bronze or steel, or any other suitable spring metal.

These laminations are initially curved downwardly, as shown at their central portion 56 in Fig. 2, and are provided with registering apertures so that the spring assembly has a centrally located aperture 51.

The body H has its web l3 provided with a lower p'ortionf58 (Fig. 1), which is integrally joined to a cylindrical sleeve portion 59 that extends downwardly'below the movable jaw 43. Side flanges 42 are also integrally joined to a forwardly extending bottom flange 50, which drical sleeve 59.

, ,The. sleeve 59 is provided-with avertically ex tending threaded bore Bl for receiving the threaded shank 62 of an eye bolt 63. .The

threaded shank 62 supports an eyestructure 64 .at its lower end, which is provided with a circular aperture 65 of suflicient size so that the .eye may cooperate with standard clamp stick' cylindrical portion 64 which provides an annular shoulder 65. A washer 66 may be mounted on .the reduced cylindrical portion 64; and the up- ;perend of this cylindrical portion may be riveted over at 6'! to secure the eye bolt to the springs.

Thus the springs are secured beneath the washer 66, which provides one'thrust bearing,

land above the annular shoulder 68, which provides a lower thrust bearing; and the reduced cylindrical portion 6.3a provides a trunnion rotatably mounted in the bore 51 of the springs, which provides a rotating bearing.-

The springs are spaced from the lower side 69 (Fig. 2) of the movable jaw 43, and thismovable jaw may have a central depression 10 formed in its lower side for receiving the riveted end -61 of the screw bolt and providing a firm bearing surface between the screw bolt and the movable jaw 43 when the screw bolt is driven-home, as shown in Fig. 3.

'; -In. order to prevent placing a strain on the rivet end 61 when the screw bolt 63 is backed out, this bolt may have its threaded shank B2 spun :oveivat H at the annular shoulder 63 to prevent the screw bolt from being moved downwardly beyond a predetermined point.

It is preferablealso to provide the threaded bore 6| and threaded shank 62 with relatively loose standard threads and to provide the front and back of the sleeve 59 with axially extending slots 12. These lower slotted portions of the sleeve 59 may then be pressed together, before the screw bolt 63 is inserted, so that the'lowe'r portions form resilient jaws l3, 14 which resiliently grip the threaded shank62 of the screw bolt.

' The loose threads will give suflicient clearance so that any corrosion will not prevent the upper part of the bore 6| fromfreezing tothe-screw bolt, and the lower resilient jaw portions '53, 14 of the sleeve 59 will not freeze to the threaded shank 62 because they can be made to give and can be loosened by inserting a screwdriver in the slot 12. Thus the present tap connector is ,so constructed that it will never stick on the line so tightly that it cannot be removed.

The upper jaw through I2 is preferably provided with a slight downward bulge at'l5 midway between its ends to correspond to the tension sag in the electrical line and to fit the conductor 4| better. The lower movable jaw, 43 may be given a complementary downwardly extending concavity 16 midway between its ends, thus curving both the upper and lowerjaws to correspond, to

the sag in the electrical line 23nd providing better. lines of contact.

The mode of assembly of thethreaded member, spring assembly, and movable jaw is as follows: The eye bolt is threaded into its bore until its reduced endprojects from the upper end of the bore. The spring assembly is then placed on the reduced cylindrical portion 63a of the eye bolt,-the washer is applied, and the further reduced end 64 is riveted over at 61.

The movable jaw may then be slid endwise, with its lugs 52 passing into the slots 54, and the assembly may be inverted and placed upon a suitable anvil having a surface which fits the angular surfaces 50, 5| of the movable jaw. As the ends of the lugs 52 then project beyond the lower flange 60, the ends of the lugs 52 may then be riveted over to secure the spring assembly and movable jaw together. w

The-operation of the tap clamp-connector is as follows: It has already been pointed out how the jumper wire is, gripped at a U-shaped portion which issnubbed around a lug I5 so that there is a maximum contact area and the jumper cannot dropout. The tap clamp is applied to the line in the same way as other clamps, by be- 7 ing lifted by means of a clamp stick, the screw bolt 63 being turned by means of its'eye structure 64 from the position ofFig. 2 to that of Fig. 3.

As the jaws 43 and I2 engage the line conductor 4|, the jaw 43 willslide upward, While the screw bolt 63 will rotate and the laminated spring assembly 53 will move from its downwardly bowed position in Fig. 2 to a substantially straight position, in Fig. 3. At this time the end Glof the screw bolt engages the complementary bearing surface 49 on the bottom of themovable ,jaw 43 and enables the screw bolt to effect a rigid clamping action which assures a tight clamping action on the line 4|.

Four lines oftcontact are provided, which extend substantially the full length of the flanges that form the jaws, from side to side of the clamp,

The present clamp provides a rigid contact whichhas resilience that is adapted to take up any wearor reductionin size orshape of the conductor, so thatv it will remain-in tight clamping condition substantially throughout its full life;

but it may also be removed because of .the resilient locking action of the sleeveon the threaded shank .and'becauseof the relatively loose threads between the threaded shank and sleeve.

,Itwill thus be observed that the improved tap clamp will provide a-firm and low contact resistance connection on a conductor of a transmission line or any other conductor, in spite of vibration which might batter the metal of the line, and in spite of the flowing of the metal away from contact pressure points. Even though the conductor strands mush somewhat or the screw backs off somewhat, the contact will be maintained by the resilient connection between the eye bolt and the movable jaw and corrosion between the jaws and the conductor will be prevented as long as there What is claimed is:

1. In a tap clamp of the screw type, the combination of a body memberwhich is provided with an integral forwardly extending fixed jaw, having a trough for receiving the line conductor, said body member being provided with a threaded bore and a threaded member in said bore, a movable jaw guided on said body member into alignment with the fixed jaw, and a resilient connection between said movable jaw andsaid threaded member, whereby the line conductor may be resiliently clamped by said movable and fixed jaw under the influence of said threaded member in said threaded bore, said resilient connection comprising a laminated spring assembly rotatably mounted on said threaded member and having its ends secured to said movable jaw.

2. In a tap clamp of the screw type, the combination of a body member which is provided with an integral forwardly extending fixed jaw, having a trough for receiving the line conductor, said body member being provided with a threaded bore and a threaded member in said bore, a movable jaw guided on said body member into alignment with the fixed jaw, and a resilient connection between said movable jaw and said threaded member, whereby the line conductor may be resiliently clamped by said movable and fixed jaw underv the influence of said threaded member in said threaded bore, said resilient connection comprising a laminated spring assembly rotatably mounted on said threaded member and having its ends secured to said movable jaw, said laminated spring assembly and threaded member being spaced from the adjacent portion of said movable jaw, whereby the application of pressure, to the resilient connection by the threaded member in clamping a conductor initially tensions said resilient connection, and thereafter the threaded member fixedly engages the movable jaw and effects a fixed clamping action on the conductor.

3. In a tap clamp, the combination of a metal body provided with a rearwardly extending web and having an upper forwardly extending jaw defined by laterally extending flanges and forming a ll-shaped trough, said web also carrying laterally extending fiangesalong its forward face for guiding a movable jaw and supporting a depending sleeve provided with a threaded bore, a threaded eye bolt in said threaded bore, said eye having its shank provided with a reduced cylindrical end portion forming a trunnion, a plurality of leaf springs forming a laminated spring assembly provided with a centrally located bore lolaterally extending flanges along its forward face for guiding a movable jaw and supporting a depending sleeve provided with a threaded bore, a threaded eyebolt in said threaded bore, said eye having its shank provided with a, reduced cylindrical end portion forming a trunnion, a plurality of leaf springs forming a laminated spring assembly provided with a centrally located bore located on said trunnion and a movable jaw carried 'by the'en'ds of said leaf springs, said movable jaw having a V-shaped clamping surface, said threadestates 8 ed eyebolt having its end threaded portion deformed to prevent retraction of the eye bolt and strain on the spring supporting portion.

5. In an electrical connector of the tap clamp type, the combination of a metal body member provided with an integral forwardly extending fixed jaw, said body member havin a threaded bore oppositely disposed to said jaw, a threaded member in said bore and provided with a head adapted to be actuated by means of a clamp stick or the like, a spring rotatably mounted on the end of said threaded member, and a movable jaw carried by said spring in opposition to the fixed jaw, the threaded member and spring urging the movable jaw into engagement with a conductor between said jaws, the said threaded member being initially spaced from said movable jaw by said spring and said threaded member flexing the spring until the threaded memberengages the movable jaw to drive it into fixed clamping relation with said conductor, the spring remaining flexed and ready to take up any looseness between said conductor and said movable jaw, the said spring comprising an elongated flat spring having a central aperture for receiving 'a reduced riveted portion of said threaded member, the ends of said elongated spring engaging said movable jaw at points equally spaced from the axis of said threaded member.

6. In an electrical connector of the tap clamp type, the combination of a metal body member provided with an integral forwardly extending fixed jaw, said body member having a threaded bore oppositely disposed to said jaw, a threaded member in said bore and provided with a head adapted to be actuated by means of a clamp stick or the like, a spring rotatably mounted on the end of said threaded member, and a movable jaw carried by said spring in opposition to the fixed jaw, the threaded member and spring urging the movable jaw into engagement with a conductor between said jaws, the said threaded member being initially spaced from said movable jaw by said spring and said threaded member flexing the spring until the threaded member engages the movable jaw to drive it into fixed clamping relation with said conductor, the spring remaining flexed and ready to take up any looseness between said conductor and said movable jaw, the said spring comprising an elongated spring having a central aperture for receiving a reduced riveted portion of said threaded member, the ends of said elongated spring engaging said movable jaw at points equally spaced from the axis of said threaded member, and said spring being assisted by a plurality of similar elongated springs arranged one upon the other in a stack on said threaded member.

7. A hot line connector including a body portion provided at its upper end with the fixed element of a clamp for overlappin a conductor, an eye bolt threaded through the lower part of the body portion, a one-piece substantially rigid head constituting the movable element of the clamp pivotally connected to the adjacent end of the eye-bolt, said head provided on its underside with a centrally located recess forming a pair of inwardly facing shoulders, a bowed spring plate fitted in the recess with its opposite edges facing and normally spaced from the shoulders and said shoulders limiting the distention of the spring plate and said eye bolt provided with a flange for engaging the spring plate and acting therethrough to force the head resiliently into engagement with the underside of the conductor.

8. The connector defined in claim 7 and in which one of the conductor engaging faces of one clamp element is convex in the direction lengthwise of the conductor and the corresponding face of the other clamp element is similarly concaved, whereby the conductor is kinked by the squeeze action of the clamp elements and tends to assume the contour imposed thereon by the convex face of the first-named clamp element.

CORNELIA SMARTT HENDLEY, Executrim of the Will 0 Flavius Josephus Hend- Zey, Deceased.

REFERENCES CITED The following references are of record in the file of this patent:

Number 10 UNITED STATES PATENTS Name Date Anthony Nov. 1, 1921 Eberling June 15, 1925 McCracken Nov. 25, 1929 Freebury June 6, 1933 Bodendieck Dec, 18, 1934 Yonkers July 2, 1940 Johnson Aug. 19, 1941 Williams Nov. 25, 1947 Thompson Aug. 31, 1948 

